Management of septic arthritis: a systematic review

OBJECTIVE

To evaluate the existing evidence on the diagnosis and management of septic arthritis in native joints.

DESIGN

Systematic review.

DATA SOURCES

Cochrane Library, Medline, Embase, National Electronic Library for Health, reference lists, national experts.

REVIEW METHODS

Systematic review of the literature with evaluation of the methodological quality of the selected papers using defined criteria set out by the Clinical Effectiveness and Evaluation Unit of the Royal College of Physicians.

RESULTS

3291 citations were initially identified. Of these, 189 full text articles were identified for potential selection. Following review of these full text articles, 80 articles were found to fulfil the inclusion criteria and were included in the final list.

CONCLUSIONS

were drawn on the diagnosis, investigation and management of septic arthritis.

DISCUSSION

Little good quality evidence exists to guide the diagnosis and management of septic arthritis. Overall, no investigation is more reliable in the diagnosis of septic arthritis than the opinion of an experienced doctor. Aspiration and culture of synovial fluid is crucial to the diagnosis, but measurement of cell count is unhelpful. Antibiotics are clearly required for a prolonged period, but there are no data to indicate by which route or for how long. Key unanswered questions remain surrounding the medical and surgical management of the infected joint.

Joint damage and disability in rheumatoid arthritis: an updated systematic review

Joint damage and disability in rheumatoid arthritis (RA) both increase with disease duration but the nature of their relationship is uncertain. This review updates knowledge of the progression and inter-relationship of joint damage and disability in treated RA and provides a synopsis of the main predictive factors for damage and disability. In early RA 39-73% of patients develop one or more erosions in their hands and wrists by 5 years. In established RA the average annual increase in radiological damage scores is 1.9% maximal damage. After 20 years RA patients have on average 43% of maximum possible damage. These data suggests that joint damage progresses constantly over the first 20 years of RA. The average annual increase in HAQ scores is 0.033 per year (1% of possible maximum disability). In the first years of disease there is a "J-shaped" curve with an initial fall in HAQ scores followed by an increase over the next four years. In cross-sectional studies there is either no correlation or a weak correlation between damage and disability in early RA; this absence of correlation is explained by the "J-shaped" curve of disability with disease duration in early RA. As disease duration increases the correlation between damage and disability becomes more obvious; 9 studies show correlation coefficients between 0.31 and 0.75. The most predictive factors of damage and disability are rheumatoid factor status and disease activity. The validity of our conclusions are limited by the potential indirect link between small joint damage and disability, with large joint damage being a more important predictor, and the presence of ceiling effects on X-rays. In conclusion, joint damage accounts for a substantial proportion of the disability associated with the disease.

On the difficulties of establishing a consensus on the definition of and diagnostic investigations for reactive arthritis. Results and discussion of a questionnaire prepared for the 4th International Workshop on Reactive Arthritis, Berlin, Germany, July 3-6, 1999

OBJECTIVE

There is no agreement on how to classify and diagnose reactive arthritis (ReA) and it is also unclear what kind of specific clinical and laboratory investigations are appropriate. We define relevant points of agreement and identify points of disagreement among an international group of experts in the field.

METHODS

Prior to the 4th International Workshop on Reactive Arthritis, Berlin, July 1999, we sent questionnaires to 42 experts identified by personal knowledge and recent publications.

RESULTS

The response rate was 81% (n = 34). There was agreement on the nomenclature and recommendation to use the term "reactive arthritis" only if the clinical picture and the microbes involved are HLA-B27 and spondyloarthropathy (SpA) associated, whereas the term "infection related arthritis" is used for all other arthritides related to or associated with infections. A differentiation between acute and chronic ReA with a cutoff of 6 months is recommended. The history of a preceding symptomatic infection is thought to be most relevant for a diagnosis of ReA. The minimal interval between preceding symptoms and arthritis is proposed to be 1-7 days, maximally 4 weeks. The joint pattern in ReA is asymmetrical, with predominance of the lower limbs. SpA related symptoms may contribute to the diagnosis. A search for chlamydia in urine/urethra/cervix is recommended, while in the case of diarrhea enterobacteria should be searched for in stool and antibodies against them in serum. There were also areas of disagreement, such as: Is arthritis essential for the diagnosis of ReA?, Is it oligoarthritis or any arthritis?, What are the role and value of polymerase chain reaction investigation?, The role and value of serology?, Is the diagnostic sensitivity of microbiological tests for ReA increased by HLA-B27 determination?

CONCLUSION

The points of agreement will support better communication in this area, and clarification of the disagreements will lead to further studies and discussion.

Corticosteroids inhibit lymphocyte binding to endothelium and intercellular adhesion: an additional mechanism for their anti-inflammatory and immunosuppressive effect

Glucocorticosteroids (GCS) are potent anti-inflammatory and immunosuppressive agents widely used in the treatment of many medical conditions, but their mechanism of action is not yet fully understood. Some of the anti-inflammatory effects of GCS have been attributed to the synthesis of lipocortins, whereas the immunosuppressive effects are thought to be mediated through the inhibition of several immune functions through a down-regulation of cytokine gene expression. Another important mechanism of action of GCS may relate to their ability to interfere with the phenomena of adhesion and migration of inflammatory cells. In this study, the direct effects of GCS on lymphocyte adhesion capacity in vitro were investigated. We demonstrate that GCS inhibit lymphocyte adhesion to endothelium through the down-modulation of lymphocyte adhesion molecules. We also provide evidence that GCS inhibit cell aggregate formation induced by TCR ligation, which directly correlates with the down-modulation of LFA-1 and CD2, but not LFA-3 or ICAM-1. Such down-modulation was paralleled by a decrease in the steady state mRNA level of LFA-1 and CD2 gene products, which suggests a direct GCS control of the expression of these genes. Finally, we show that GCS effects are mediated through the GCS receptor, since they can be completely reversed by the GCS-R antagonist RU-486. This study supports the concept that some of the immunosuppressive and anti-inflammatory effects of GCS are likely to be exerted by the inhibition of adhesion-dependent lymphocyte functions.

Corticosteroids inhibit lymphocyte binding to endothelium and intercellular adhesion: an additional mechanism for their anti-inflammatory and immunosuppressive effect

Glucocorticosteroids (GCS) are potent anti-inflammatory and immunosuppressive agents widely used in the treatment of many medical conditions, but their mechanism of action is not yet fully understood. Some of the anti-inflammatory effects of GCS have been attributed to the synthesis of lipocortins, whereas the immunosuppressive effects are thought to be mediated through the inhibition of several immune functions through a down-regulation of cytokine gene expression. Another important mechanism of action of GCS may relate to their ability to interfere with the phenomena of adhesion and migration of inflammatory cells. In this study, the direct effects of GCS on lymphocyte adhesion capacity in vitro were investigated. We demonstrate that GCS inhibit lymphocyte adhesion to endothelium through the down-modulation of lymphocyte adhesion molecules. We also provide evidence that GCS inhibit cell aggregate formation induced by TCR ligation, which directly correlates with the down-modulation of LFA-1 and CD2, but not LFA-3 or ICAM-1. Such down-modulation was paralleled by a decrease in the steady state mRNA level of LFA-1 and CD2 gene products, which suggests a direct GCS control of the expression of these genes. Finally, we show that GCS effects are mediated through the GCS receptor, since they can be completely reversed by the GCS-R antagonist RU-486. This study supports the concept that some of the immunosuppressive and anti-inflammatory effects of GCS are likely to be exerted by the inhibition of adhesion-dependent lymphocyte functions.

Joint destruction in rheumatoid arthritis: biological bases

The pathogenesis of rheumatoid arthritis (RA) can be explained through two main hypotheses: macrophage-fibroblast and macrophage-T cell interactions. The interplay between the various populations is influenced by a strong genetic component, which determines the severity of the disease in some cohorts of patients attending referral centers. The key question of the nature of the antigen(s) driving joint inflammation still remains unsolved. Exogenous antigens such as viruses or bacteria have long been searched for in the synovial fluids as well as in tissues, but convincing evidence of their pathogenic role are lacking. Data have been accumulated on the possible role of autoantigens, such as the spliceosomes, filaggrin, calpastatin, type II collagens, or other endogenous peptides, but no definite role regarding their potential contribution to the activation of T cells has been established. Once the process starts, a progressive recruitment of inflammatory T cells and macrophages into the joints occurs through a complex series of adhesion and migratory events. The key driving steps leading to synovial inflammation and cartilage destruction, along with the potential contribution of some key molecules, have been described, thus opening possible perspectives for a therapeutic approach.

A comparison of conflict tactics in the supervisory process

This study investigated three different tactics clinical supervisors in communication disorders predicted they would use in a specific conflict situation. One hundred-sixty supervisors were asked to read one of three case scenarios describing a conflict situation within the supervisory process. All scenarios depicted a student-clinician who had not completed a reading assignment requested by the supervisor. The scenarios differed only in the supervisee's response to the supervisor's question about the incomplete assignment. Subjects were asked to indicate how likely they might be to use each of 15 comments that reflected categories of conflict tactics: avoidance, competitive, or collaborative tactics. Supervisors' choice of tactics differed depending on the response of the supervisee. Overall, supervisors most often chose collaborative responses, followed by avoidance responses and (least often) competitive responses. Implications are discussed in terms of impact on the supervisory process in communication disorders.

Peripheral blood and synovial fluid monocyte expression of interleukin 1 alpha and 1 beta during active rheumatoid arthritis

OBJECTIVE

To investigate the mononuclear cell (MNC) types from peripheral blood (PB) and synovial fluid (SF) of patients with rheumatoid arthritis (RA) expressing interleukin-1 beta and -1 alpha (IL-1 beta, IL-1 alpha).

METHODS

PB and SF MNC from 16 patients with classical or definite RA and controls were analyzed by flow cytometry for IL-1 beta and IL-1 alpha staining.

RESULTS

MNC from normal individuals do not stain for either IL-1 beta or IL-1 alpha. By contrast, PB and SF CD14+ monocytes from patients with active RA show significant staining for surface and intracellular IL-1 beta and IL-1 alpha. Furthermore, the erythrocyte sedimentation rate (ESR) correlates with the surface expression of IL-1 alpha (r = 0.52, p < 0.05) while the number of active joints (i.e., tender and/or swollen) correlate with the intracellular expression of IL-1 beta (r = 0.58, p < 0.03) in CD14+ monocytes.

CONCLUSION

The analysis of IL-1 beta and IL-1 alpha expression on CD14+ monocytes from peripheral blood by flow cytometry could be a potential immunological marker of disease activity in RA and its variation could be used to monitor the effects of therapy.

How do second-line agents work?

The pathogenesis of rheumatoid arthritis remains unknown. Disease modifying anti-rheumatic drugs are commonly used to treat rheumatoid arthritis patients. Their use in rheumatoid arthritis was discovered serendipitously and their modes of action remain unknown. This article reviews current hypotheses on the mechanisms of action of established DMARDs. Most of them have anti-inflammatory properties and some are immunomodulators. We also discuss a number of novel agents which are potential new DMARDs.

Adhesion molecules in rheumatoid arthritis: role in the pathogenesis and prospects for therapy

The essential role played by cell adhesion and migration in the generation of chronic synovitis is now beyond doubt. Some of the beneficial effects of currently used drugs may be related to their ability to interfere with these mechanisms. The complexity of the process, however, means that there are many potential targets for therapeutic intervention and therefore further studies of the basic mechanisms are necessary to identify those which are most important.

Monoclonal antibody therapy in rheumatic disease

In rheumatic disease, monoclonal antibodies have been used for the treatment of refractory rheumatoid arthritis, systemic lupus erythematosus, unresponsive vasculitis and relapsing polychondritis. Our greatest experience has however been with rheumatoid arthritis. After molecular engineering, hybrid monoclonal antibodies constructed from animal sources become largely human, and thus well tolerated, and highly specific. They can be focused selectively to particular targets, but the problem is to identify the causative antibody. In rheumatoid arthritis, we do know a great deal about the pathogenesis of the disease and rational targets can be selected. The major histocompatibility complex class II molecules would theoretically be the most effective target, but no specific antigen has been identified. Total blockade of all class II molecules would probably result in unacceptable immunosuppression. Despite this handicap, anti-HLA-DR4 monoclonal antibodies have been used in humans in an attempt to generate an anti-idiotypic response against DR4. T lymphocytes are known to play a major role in the pathogenesis of rheumatoid arthritis, thus targeting their surface markers would be a reasonable approach to monoclonal antibody therapy. Trials have been conducted using antibodies against the surface markers CD7, CD5, CDw52 and CD4. Further work has centered on differentiation antigens. Preliminary evidence suggests anti-interleukin-2-receptor monoclonal antibodies may be effective in rheumatoid arthritis. There have also been reports of attempts at anti-cytokine immunotherapy. Adhesion molecules would be another potential target. The ongoing trials have given us much insight into the pathogenesis of rheumatoid diseases and led us to the stage where we are now attempting to identify appropriate therapeutic regimes and combinations to maximise patient benefit. At present, we must continue our research for the causative antigen.

Current perspectives in reactive arthritis

Reactive arthritis (ReA) is an inflammatory arthritis triggered by infection, usually urethritis or gastroenteritis, and is strongly associated with the MHC class I antigen HLA-B27. Two recent observations have excited interest: first, antigen and DNA from the triggering bacteria have been identified in the joint and, second, ReA synovial T cells have been found to respond specifically to the bacterium that caused the initiating infection. Because the trigger of ReA, its onset and the MHC association are all clearly defined, we can investigate hypotheses that are impossible to study in other forms of human arthritis. Here, Gabrielle Kingsley and Jochen Sieper review the topic in the light of a recent workshop.

Excessive and dysregulated secretion of prolactin in rheumatoid arthritis: immunopathogenetic and therapeutic implications

Prolactin (PL) is essential for the normal function of the immune system. It is required for the induction of a number of autoimmune conditions in experimental animals. The role of prolactin in the immunopathogenesis of autoimmune human disease has not been established. RA is characterized by a variety of immune and inflammatory processes which determine disease activity. It has a pronounced diurnal periodicity with a peak at 03.15 hours. Since PL has a diurnal rhythm of secretion in man with a peak at about 02.00 hours, it may contribute to the nocturnal worsening of RA. We show that patients with RA secrete an excess of prolactin as evidenced by an upregulated diurnal periodicity and an abnormal increase in plasma prolactin concentration following surgery. By contrast, patients with chronic osteomyelitis, who had chronic inflammation of similar severity to patients with RA, had a normal prolactin diurnal rhythm and response to surgery. Hence, the abnormal changes in prolactin physiology seen in RA appear to be a feature of the disease per se rather than related to chronic inflammation. The elevated levels of prolactin may contribute to disease activity by augmenting immune processes and may be an additional genetic factor, independent of HLA-DR4, in the immunopathogenesis of RA. Furthermore, the effective inhibition of prolactin secretion and/or action may have potential as therapy for RA.

Systemic sclerosis occurring in a patient with Adamantiades-Behçet's disease

We report a patient who developed SS while being treated with azathioprine for ABD. This is a hitherto unreported association between the two conditions.

T cells are responsible for the enhanced synovial cellular immune response to triggering antigen in reactive arthritis

In reactive arthritis (ReA) there is specific proliferation of synovial fluid (SF) mononuclear cells (MNC) to the triggering bacterial antigen; comparatively little or no response is seen in peripheral blood (PB). To investigate the mechanism of this elevated local immune response, we examined patients with typical ReA who showed an enhanced antigen-specific synovial immune response in bulk culture. Using separated fractions of T cells and antigen-presenting cells (APC) from PB and SF we showed that the synovial T cells rather than SF APC are responsible for the specific proliferation. By limiting dilution analysis, the frequency of T cells responding to the specific antigen was found to be significantly increased compared with the frequency of irrelevant antigen-specific T cells. Furthermore, the frequency of T cells responding to the specific antigen was higher in SF (between 1/619 and 1/4846, mean 1/2389) than in PB (between 1/1286 and 1/16,279, mean 1/7350). We conclude that the specific synovial cellular immune response in ReA is mainly due to an expansion of antigen-specific T cells within the joint. However, the non-specific hyper-reactivity of SF T cells and differences between SF and PB APC may make a more minor contribution.

The immunopathogenesis and immunotherapy of autoimmune disease

A conference entitled 'The Immunopathogenesis and Immunotherapy of Autoimmune Disease' was held at the Royal College of Physicians on 20 May 1992. Its aim was to consider advances in pathogenesis and their translation into therapeutic targets.

Cellular responses to human chondrocytes: absence of allogeneic responses in the presence of HLA-DR and ICAM-1

To assess the accessory cell function of human articular chondrocytes, we assessed the ability of human chondrocytes to stimulate allogeneic peripheral blood mononuclear cells (PBMC) and to support phytohaemagglutinin (PHA)-induced proliferation of highly purified T cells. We also examined the surface expression of HLA-DR and ICAM-1 on the chondrocytes both unstimulated and stimulated with cytokines in vitro. Chondrocytes failed to stimulate allogeneic PBMC despite the constitutive expression of MHC class I molecules and the cytokine-induced expression of class II molecules but were able to support T cell proliferation to PHA, IFN-gamma and to a limited extent, IL-1 beta, induced class II expression on chondrocytes. ICAM-1 was present on 94-99% of freshly isolated cells; this declined with culture (17-59%; P < 0.005) but was readily induced by IFN-gamma, IL-1 beta, and tumour necrosis factor-alpha. Alloreactivity and, presumably, autoreactivity to chondrocytes requires factors in addition to the surface expression of DR and ICAM-1. However the presence of these molecules suggests a capacity for cell-cell interactions in inflammatory sites such as the cartilage pannus junction.

Aetiological role of bacteria associated with reactive arthritis in pauciarticular juvenile chronic arthritis

BACKGROUND

The cause of juvenile chronic arthritis (JCA) is unknown. Pauciarticular JCA is the most common subtype and can be subdivided into early (type I) and late onset (type II) forms, the latter clinically resembling reactive arthritis.

METHODS

The cellular immune responses to bacteria associated with reactive arthritis in blood and synovial fluid from 39 children with pauciarticular JCA, three children with classical reactive arthritis, and two children with psoriatic arthritis were examined. Specific titres of antibodies to bacteria in serum samples were measured in all patients.

RESULTS

A bacteria specific synovial cellular immune response was found in two of three (67%) patients with reactive arthritis and 14 of 28 (50%) patients with pauciarticular JCA type II but only in one of 11 (9%) patients with pauciarticular JCA type I and none in patients with psoriatic arthritis. Six patients responded specifically to Chlamydia trachomatis and 11 to Yersinia enterocolitica. Antigen specific lymphocyte proliferation correlated poorly with the specific antibody response.

CONCLUSIONS

These findings suggest that bacteria with associated reactive arthritis may have a causative role in pauciarticular JCA type II but not in JCA type I.

Defective hypothalamic response to immune and inflammatory stimuli in patients with rheumatoid arthritis

OBJECTIVE

To determine the integrity of the hypothalamic-pituitary-adrenal (HPA) axis responses to immune/inflammatory stimuli in patients with rheumatoid arthritis (RA).

METHODS

Diurnal secretion of cortisol and the cytokine and cortisol responses to surgery were studied in subjects with active RA, in subjects with chronic osteomyelitis (OM), and in subjects with noninflammatory arthritis, who served as controls.

RESULTS

Patients with RA had a defective HPA response, as evidenced by a diurnal cortisol rhythm of secretion which was at the lower limit of normal in contrast to those with OM, and a failure to increase cortisol secretion following surgery, despite high levels of interleukin-1 beta (IL-1 beta) and IL-6. The corticotropin-releasing hormone stimulation test in the RA patients showed normal results, thus suggesting a hypothalamic defect, but normal pituitary and adrenal function.

CONCLUSION

These findings suggest that RA patients have an abnormality of the HPA axis response to immune/inflammatory stimuli which may reside in the hypothalamus. This hypothalamic abnormality may be an additional, and hitherto unrecognized, factor in the pathogenesis of RA.

Enumeration of interleukin-1 alpha and beta producing cells by flow cytometry

A technique for intracytoplasmic immunofluorescence staining to detect and quantify human interleukin-1 alpha (IL-1 alpha) and beta (IL-1 beta) in CD4, CD8, and CD14 positive lymphoid cells is described. Mononuclear cells stimulated in vitro with PHA to produce IL-1, were fixed and made permeable to antibodies by sequential exposure to paraformaldehyde and the detergent n-octyl-glucoside. Cytoplasmic and surface staining of both forms of IL-1 were demonstrated by indirect fluorescence using IL-1 beta and IL-1 alpha specific mouse monoclonal antibodies and quantified with flow cytometry.

Alteration in T cell/macrophage ratio may reveal lymphocyte proliferation specific for the triggering antigen in reactive arthritis

It has previously been shown that synovial fluid (SF) mononuclear cells (MNC) from patients with reactive arthritis (ReA) and some patients with undifferentiated oligoarthritis (UOA) respond specifically to the triggering bacterium (specific responders). However, in some patients there is a response to two or more bacteria (non-specific responders) and in a third group no response is found (non-responders). We assessed whether the proportion of synovial MNC which were macrophage-monocyte (MaMo) differed among the specific responder, non-specific responder and non-responder groups. There was no difference between the specific (33 +/- 9) and the non-specific (32 +/- 26) groups; non-responders had a higher percentage of MaMo (61.3 +/- 31%) although the difference was not significant. We also investigated whether the specificity of the response to antigen in ReA or UOA SF was altered by changing the T-cell/MaMo ratio. In all five specific responders the immune response remained specific whatever the ratio tested. However, four of the five non-specific responders, but none of the non-responders, developed a specific response to one of the tested antigens by increasing the T cell/MaMo ratio. We conclude that in some patients with a non-specific response, alteration of the T cell/MaMo ratio uncovers a specific response which may identify the triggering antigen.

Pathogenetic role of Chlamydia, Yersinia and Borrelia in undifferentiated oligoarthritis

We studied the cellular and humoral immune response to Chlamydia trachomatis, Yersinia enterocolitica and Borrelia burgdorferi in paired samples of peripheral blood and synovial fluid (SF) in undifferentiated oligoarthritis, reactive arthritis (ReA) and rheumatoid arthritis. Antigen specific lymphocyte proliferation was found in SF of 43% of patients with ReA and 34% of patients with undifferentiated oligoarthritis. C. trachomatis was the most frequent single agent. HLA-B27 was positive in 83% of patients with ReA and in 62% of patients with undifferentiated oligoarthritis with antigen specific lymphocyte proliferation. Antigen specific lymphocyte proliferation correlated poorly with the specific antibody response. Only chlamydial antigen was detected in SF cells using monoclonal antibodies. We conclude that some patients with undifferentiated oligoarthritis may have a forme fruste of ReA. This finding is important in view of recent evidence supporting the efficacy of antibiotic therapy in ReA.

Management of early inflammatory arthritis. Intervention with immunomodulatory agents: T cell vaccination

Current theories of the aetiology of RA point to a central role for the trimolecular complex comprising the MHC class II molecule on the surface of the APC, the antigenic peptide and the TCR on the disease-inducing T cell. Thus the arthritogenic T cell is an important target for new therapy. However, it cannot be directly identified because the causative antigen is unknown, so indirect techniques such as TCV and TCR peptide vaccination are required. In TCV, T cells thought to mediate the disease, in an activated and attenuated form, are injected into the patient, who then develops a specific immune response against these pathogenic T cells. TCV has been shown to be effective in protecting against and treating a variety of animal models of autoimmune disease, including AA, EAE and IDDM in NOD mice. The vaccines initially comprised clones and lines of T cells shown to be capable of transferring the disease, but later unseparated LN cells were also shown to be effective, paralleling more closely the human situation. Interestingly, it has become clear that TCV does not create its own regulatory network but amplifies a natural immunoregulatory network which forms as the disease develops. The major stimulating moiety on the vaccinating T cell is its receptor (anti-idiotypic response), although there is also an anti-ergotypic (anti-activated T cell) response. For this reason the technique of TCR peptide vaccination was developed, which utilizes only a short peptide from the TCR of the disease-causing cells to stimulate an immune response against them. This is effective in the prevention and treatment of EAE, where there is a preferential usage of TCR-V beta 8 by encephalitogenic T cells. The application of both these techniques to human autoimmune disease is in its infancy. Studies of TCV in MS and RA have not shown clear-cut clinical benefit, although immunological changes have been observed; comparison of methodology with the animal work and assessment of results are complex and further studies are in progress. Studies of TCR peptide vaccination in MS and RA are handicapped by the lack of a consensus on TCR usage in these conditions, but a limited study is underway in MS.

Class II MHC binding peptides: a feasible treatment for arthritis?

The association of rheumatoid arthritis with the MHC class II alleles HLA DR4 and HLA DR1 may be due to their capacity to present an arthritogenic peptide to T cells, thus inducing the disease. Interfering with this presentation using a competitor peptide would inhibit the disease and such therapy has been effective in animal models. These studies, and the possibility of transferring the therapy to humans, will be reviewed.

Antigenic responses in reactive arthritis

In this article, the mechanisms by which infection at a distant site could lead to ReA and whether they could explain the association of ReA with HLA-B27 have been discussed. We propose that ReA synovitis is primarily due to specific synovial T-cell proliferation to fragments of the triggering bacterial found in the joint. Nonspecific T cells amplify synovitis with antibodies playing only a secondary role. First, we have shown that the triggering bacterial antigen is present in a nonviable form in ReA synovium and that this, not cross-reactive joint autoantigen, stimulates the specific synovial immune response. Second, the studies of the humoral immune response in ReA have been reviewed. Further evidence of bacterial persistence in the joint comes from work demonstrating intrasynovial bacteria-specific antibody synthesis. Continuing maturation of the antibody response also points to persisting antigen. In enteric but not genitourinary ReA, the humoral response is mainly IgA, implying chronic stimulation of the gut mucosa. Analysis of the molecules against which the humoral response is directed has shown no difference between yersinia arthritis and yersiniosis, but in CTA, the response to the 57kD and 59kD antigens differs from CT urethritis suggesting they may be arthritogenic. Finally, the antibody response may be absent in ReA patients rendering antibody titres diagnostically less useful and confirming their secondary role in the pathogenesis of synovitis. Third, studies of cellular response in ReA have been analyzed. We show there is a specific synovial MNC proliferative response to fragments of the triggering bacteria found in the joint, which is potentially of diagnostic use. The proliferation is due to CD4+ and CD8+ T cells and restricted by MHC class I and II antigens. This antigen-specific T-cell response is accompanied by an antigen-independent recruitment of nonspecific T cells, which may contribute to the amplification of synovitis. The importance of the synovial APC in determining the synovial immune response is unarguable but the exact mechanisms are unclear. Further details on the possible role of HLA-B27 in the presentation of arthritogenic peptides and on the exact identity of the antigenic epitopes recognized in ReA must await analysis of a large panel of T-cell clones. Finally, it is hoped that advances in this field will lead to specific and effective immunologic therapies or vaccines for this currently untreatable disease.

Inhibition of lymphocyte proliferation by a monoclonal antibody (RFT2) against CD7

The effect of the monoclonal antibody RFT2, directed against CD7, on T cell proliferation in unseparated peripheral blood mononuclear cell populations induced by various stimulants was investigated. The addition of RFT2 to cell cultures inhibited the T cell proliferation induced by tuberculin PPD and OKT3 but not by phytohaemagglutinin, concanavalin A or phorbol myristic acid; RFT2 had to be present during the first 24 h of culture in order to elicit inhibition; inhibition of proliferation was not due to down regulation of interleukin-2 receptor on the surface of T cells; and suppressive effects could be transferred by mononuclear cells pre-treated with RFT2. These results are of particular relevance in view of the known in vivo suppressive effect of RFT2 in humans.

Immunotherapy of rheumatic diseases--practice and prospects

Present treatments for rheumatic diseases are both toxic to patients and largely ineffective in modifying the disease process. This report, based on a meeting recently held in London, investigates how far recent molecular and immunological advances can be converted into more effective, less toxic and, above all, more specific therapies.

Synovial T lymphocyte-specific immune response to Chlamydia trachomatis in Reiter's disease

We studied the lymphocyte proliferative response to Chlamydia trachomatis in Reiter's syndrome (RS) compared with that in other rheumatic diseases. RS patients showed significantly increased C trachomatis-specific synovial fluid (SF) T cell proliferation. Proliferating cells were found in both CD4+ and CD8+ T cell subsets. The SF lymphocyte proliferative response to C trachomatis in RS was inhibited by anti-class I and class II major histocompatibility complex monoclonal antibodies, while the response to tuberculin purified protein derivative was inhibited only by anti-class II monoclonal antibodies. T cell receptor gamma/delta-bearing T cells were not consistently increased in RS SF compared with peripheral blood, nor did such cells consistently expand upon in vitro culture with C trachomatis. Finally, there was no correlation between the cellular immune response and levels of antibody to C trachomatis antigens. Our results indicate that a specific T cell response to C trachomatis within the joint plays a role in the pathogenesis of RS.

Monocyte activation in rheumatoid arthritis: evidence for in situ activation and differentiation in joints

Monocytes, defined by staining with the Mo-2 and Leu-M3 monoclonal antibodies which both detect the CD14 antigen, were studied in peripheral blood of control subjects and patients with rheumatoid arthritis as well as in rheumatoid synovial fluid of the latter for expression of activation/differentiation markers. The monocytes in the rheumatoid synovial fluids showed increased expression of class II major histocompatibility antigens (HLA-DR and -DQ) and decreased positivity for the peanut agglutinin receptor as compared with those from patient and control peripheral blood. There were no differences in phenotype between the control and patient peripheral blood monocytes. These findings are consistent with the hypothesis that monocytes are activated and differentiate into more mature macrophage-like cells after entry into the rheumatoid joint.